Paleoceanographic condition changes in the Eastern Bransfield Basin, Antarctic Peninsula, since the late glacial interval and its implications

Abstract

Antarctic Peninsula is the most northerly area in the Antarctica, thus it is vulnerable to warming climate. Although it is well known that relatively warm water mass input onto the Antarctic shelf region facilitates ice shelf retreat, when and how the water mass exchange between the deep Southern Ocean and the Antarctic shelf regions is not well known in ice proximal areas due to sea ice dynamics on the continental shelf region. Here, we document the diatom assemblage record of a sediment core with high sedimentation rates since the late glacial interval from 34.6 ka to address surface environmental changes in the Eastern Bransfield Basin (EBB). We found that the EBB was covered by extensive sea ice showing millennial-scale variations during the late glacial interval. The sea ice started to decrease during the deglacial interval (19-11 ka) with slight increases of open ocean influence. In addition, meltwater input was significant during 14.7-11.3 ka which corresponds to Antarctic Ice Sheet Discharge events reported in the Scotia Sea including Meltwater pulse 1A and 1B. During the Holocene after 9 ka, relatively warm water mass input distinctively increased into the EBB contemporaneous with a remarkable decrease in sea ice influence indicating the strong relationship between sea ice and warm water mass input. In addition, meltwater input at 9 ka was also distinctive in the EBB, but there was no corresponding Antarctic Ice Sheet Discharge event in the Scotia Sea. Our results show how well surface environmental changes in the EBB correspond to the global climate change and the regional climatic characteristics at the same time.